Can you coinche your partner?
The answer is no: you can only coinche the opposing team, never your own partner.
Why it's impossible
To coinche is to bet that the team holding the contract will fail. Since you and your partner are on the same team, coinching them would mean betting against yourself. So the rule is simple: you only coinche the opponents who just won the auction.
Who can coinche, and when
- Only a player on the defending team (the one that did not take the bid) may coinche.
- The coinche is called before the first card is played, once the contract is set.
- After a coinche, the team that took the bid may surcoinche if they feel confident.
When your partner is declarer
If your partner took the contract, you do nothing unusual: you simply help them make it by playing well. You neither coinche nor overbid them. Your job is to bring your tricks to the team, for instance by loading their winning tricks with your big cards (10, Ace) to swell the total.
See also
FAQ
Can you coinche your partner?
No. You only coinche the opposing team that won the contract, never your own partner.
Who is allowed to coinche?
Only the two players on the team that did not take the contract can coinche, and only before the first card is played.